Deuteronomy 3:16-17

3:16 To the Reubenites and Gadites I allocated the territory extending from Gilead as far as Wadi Arnon (the exact middle of the wadi was a boundary) all the way to the Wadi Jabbok, the Ammonite border. 3:17 The Arabah and the Jordan River were also a border, from the sea of Chinnereth to the sea of the Arabah (that is, the Salt Sea), beneath the watershed of Pisgah to the east.